slide condition clojure

(let [this-num-of-slide? (fn [n] (= (:focus-slide db) (- (:slides-count db) n)))]
                                    (cond
                                        (this-num-of-slide? 2) (update db :focus-slide inc) ; если предпоследний слайд
                                        (this-num-of-slide? 1) db                           ; если последний слайд
                                        :else (-> (assoc db :current-slides (->> (nth (:current-slides db) 2)
                                                                           inc
                                                                           (conj (into [] (take-last 2 (:current-slides db)))))
                                                      :right-next-slide false)
                                                  (update :focus-slide inc))))